Grinding machine



Oct. 10, 1939.

J. G. THOMPSON 2,176,017

GRINDING MACHINE Filed Oct. 50, 1957 3 Fl'g4 JuH/v E. THuMFsu/v Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE GRINDING MACHINE Application October 30, 1937, Serial No. 171,924

1 Claim.

The invention relates to grinding machines, and with regard toits more specific features to a work head for imparting an eccentric motion to the work piece.

One object of the invention is to provide 2'. cy-

lindrical grinder adapted to grind bodies to an eccentric cylindrical contour. Another object of the invention is to provide a cylindrical grinder to grind elliptical bodies. Another object of the invention is to provide a work head for grinding machines for the grinding of eccentric and elliptical bodies. Another object of the invention is to provide a machine or an attachment for grinding elliptical automotive pistons. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts, as will be exemplified In the structure to be hereinafter described, and

the scope of the application of which will be indicated in the following claim.

In the accompanying drawing in which is illus trated one of many possible embodiments of the mechanical features of this invention,

Figure l is a front elevation of a grinding machine having the work head of the invention incorporated thereon;

Figure 2 is an end elevation of the work head,

certain parts being shown in a section taken on the line 22 of Figure 1;

Figure 3 is a horizontal axial sectional view taken on the line 3-3 of Figure 2; and.

Figure 4 is a fragmentary vertical axial sec- 5 tional view on an enlarged scale taken on the line 44 of Figure 2.

I provide a plain cylindrical grinder including, as shown in Figure l, a base I0 supporting on the usual ways for longitudinal reciprocation a table 40 or carriage II.

The machine may have the usual wheel head 20 journaling a shaft 2| upon which is mounted a grinding wheel 22. In such event there is preferably provided a motor 23 driving a pulley 24 45 which is connected by multiple belts 25 to a pulley 26 attached to shaft 2|. The usual cross slide ways, not shown, for the Wheel head 20 are also provided whereby to move the grinding wheel 22 toward and from the work piece.

5 For control of the cross feed there is provided a hand wheel 30 with a micrometer adjustment device 3| and a ratchet wheel, not shown, operated by a pawl 32 which is attached to a slide 33 operated by a connecting rod 34 eccentrically 55 attached to a disk 35. Connected to the disk 35 is a small gear, not shown, which meshes with a rack 31 on the end of an arm 38 which is connected at 39 to an arm 40 attached to the main reversing lever 4| which is positioned for contact with the usual table reversing dogs or stops 42 '5 and t3 adjustably secured to the table or carriage H. The reversing lever 4! operates a mechanical reversing mechanism, not shown, to reverse the table H first in one direction and then in the other, according to the position of the lever 10 ll. By means of a hand lever 45 the direction of travel of the table II can be reversed manually.

I provide further manually operated mechanism for moving the table or carriage Ii comprising a hand wheel mounted on the shaft 5| which is :15 attached to pinion gear 52 meshing with a large gear 53 to which is attached a pinion gear 54 meshing with a rack 55 attached to the under side of the table or carriage H. For the mechanism thus indicated, hydraulic driving and re- '20 versing mechanism may be substituted, if desired. For a fuller description of one form of grinding machine embodying many of the features heretofore indicated, reference may be had to patent to C. H. Norton No. 762,838 granted 25 June 14, 1904.

The work head of the machine is mounted upon the table or carriage II which provides the usual ways 6|, 6| to which the work head 60 may be clamped in any longitudinal position by means of the overhanging portion 62 on one side and the clamp 63 on the other side, as shown in Figure 2. On the top of the work head 60 is mounted a motor '65 which, as better shown in Figure 1, has a pulley 66 on the armature shaft 61 thereof. 35 The pulley 66 is connected by a belt 68 to a pulley 69 mounted on a shaft 10 journalled in the work head. Referring now to Figure 3, a journal H is provided for the shaft 10 in the work head. Keyed to the shaft 10 are spur gears 12 and 13 40 of different diameters. The spur gear 12 meshes with a spur gear 14 which is keyed to an eccentric sleeve 15 journalled in journals 76 in the work head 66. The spur gear 13 meshes with a spur gear-8ll which is mounted for rotation on a hub 45 8| of the gear '14, which hub is concentric with the axis of the gear 14.

The sizes of the gears 72, 13, 74 and 80 are such that the gear 14 is rotated at twice the angular velocity of gear 80. Referring now to Figures 2, 50 3 and 4, the gear 80 has an annular ridge projecting from its surface, which ridge, however, has two slots 86 therein. A disk 81 has diametrically opposite projecting arms 88 which fit in the slots 86. The disk 81 is attached by 55 screws 89 to a sleeve 90 which is journalled in journals 9| in the sleeve 15. The journals 9| are, however, eccentrically located in the sleeve 15 and revolve with it. Thereby a rotating motion is given to the axis of the sleeve 90 as it revolves.

The work piece A tobe ground is the piston of an automobile having a wrist pin bore B. I provide a long spindle 94 in the sleeve 90 which has a cross pin 95 in the front end which can be located in the bore B, as shown in Figure 3. The sleeve 90 has a screw threaded portion 96 upon which fits a driving plate 91 shaped to receive the lower end of the piston A. The left-hand end of the spindle 94 is threaded and receives a hand wheel I00. By tightening the hand wheel, the pin 95 is drawn to the left against the bore B, so pressing the piston'A against the plate 91.

It will be seen that the piston A can readily be mounted in position for rotation by the work head and removed therefrom, the latter by simply releasing the hand wheel I and pressing the pin 95 out of the bore B and the spindle 94. Whenever the motor is energized with the work piece A in position to be operated upon, the work piece A Will be given such a motion that the grinding wheel 22, when brought against the work piece in the usual manner, will generate an elliptical surface thereon. From the standpoint of manufacture of an automobile, an elliptical piston has certain advantages.

The journals 9| define the axis of the work piece which is constantly changing in position since the journals 9| are fixed in the sleeve 15. The work piece is thus revolved and its axis is revolved at the same time. Since the position of the grinding wheel is relatively fixed except for the small amount of feed the work piece is thus revolving and also approaching and receding from the grinding wheel. Since the gear 14 is revolving at twice the speed of the gear the work piece advances and retreats to and from the grinding wheel twice during each revolution thereof. This will generate an elliptical surface on the work piece since considering the angular displacement of a point generating the circumference of an ellipse, it moves from and towards the center twice during a complete revolution. Furthermore the angular velocity of approach and recession is accelerated according to the sine curve law.

It should be observed, however, that if the gears 12 and 13 be of equal diameter the axis of the work piece will approach and recede from the grinding wheel once for each revolution of the work piece and thus will generate an eccentric surface on the work piece. By a small change, therefore-in the gears in this apparatus an eccentric work piece may be generated. Other shapes also may be created by still different gear ratios.

It will thus be seen that there has been provided by this invention apparatus in which the various objects hereinabove set forth together with many thoroughly practical advantages are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbeiore set forth or shown in the accompanying drawing is to be interpreted. as illustrative and not in a limiting sense.

I claim:

In a grinding machine, a table or carriage, a grinding wheel, means to move the grinding wheel toward and from the table or carriage, the table or carriage being movable parallel to the axis of the grinding wheel, and a work head comprising a support mounted on said table or carriage, a sleeve journalled in said support, a work holder journalled in said sleeve, and means to rotate both of said sleeve and said work holder, one of said parts being eccentric with respect to another of said parts.

JOHN G. THOMPSON. 

